Stretching from the frozen north of Alaska to the glacial tip of Argentina, the Pan-American Highway runs the most miles—or kilometers, if that’s your thing—of any road on Earth.

Beginning in Prudhoe Bay, or Sagavanirktok in Inuit, where caribou wander through Arctic air, the Pan-American Highway heads south to its unofficial end in Ushuaia, the capital of Argentina’s Tierra del Fuego province.

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However, the highway is not without its peculiarities. The Alaska Highway, which runs through Alaska and Canada, is the unofficial beginning of the Pan-American Highway. Once in the contiguous United States the entire Interstate Highway System is designated as part of the Pan-American Highway.

There are a couple routes—Interstate 35 is the most popular—to take south toward Mexico and Central America, where the road is known as the Inter-American Highway.

By the time it reaches Panama, the highway is interrupted twice: by the Panama Canal, where vehicles can be ferried over, and by the Darién Gap, where vehicles dare not go.

The Darién Gap is a 60-mile stretch of swampland that straddles the border of Panama and Colombia. No road exists between Yaviza, Panama, and Turbo, Colombia, because construction has been deemed too expensive. There are also concerns that a highway running through the area would damage the environment and disturb indigenous peoples.

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The highway then rolls through the jungles, mountains and deserts of South America’s Pacific coast. It passes through Ecuador, Peru, and Chile before turning east into Argentina. Once in Buenos Aires, the route unofficially continues south toward Argentina’s end.

There it once again reaches an obstruction: the Magellan Strait, over which a ferry must be taken to the archipelago of Tierra del Fuego. The second split takes motorists by boat across to Uruguay and continues up along Brazil’s coast passing through cities like São Paulo and Rio de Janeiro along Brazilian Highway 116.

The roughly 19,000 miles of the Pan-American highway represent the most extensive highway system on Earth, passing through every kind of terrain and a variety of cultures.